In an embodiment, the invention relates to a method for reducing coke agglomeration in petroleum streams derived from coking processes. In a preferred embodiment, the invention relates to a method for mitigating filter fouling from a coker gas oil wherein an oxygen scavenger is employed to remove molecular oxygen and peroxides.
Petroleum coking relates to processes for converting high boiling point, heavy petroleum feeds such as atmospheric and vacuum residuals (xe2x80x9cresidxe2x80x9d) to petroleum coke (xe2x80x9ccokexe2x80x9d) and hydrocarbon products having atmospheric boiling points lower than that of the feed. Some coking processes, such as delayed coking, are batch processes where the coke accumulates and is subsequently removed from a reactor vessel. In fluidized bed coking, for example fluid coking and FLEXICOKING(trademark) (available from ExxonMobil Research and Engineering Co., Fairfax, Va.), lower boiling products are formed by the thermal decomposition of the feed at elevated reaction temperatures, typically about 900 to 1100xc2x0 F. (about 480 to 590xc2x0 C.) using heat supplied by fluidized coke particles.
Following coking, the lower boiling hydrocarbon products, such as coker gas oil, are separated in a separation region and conducted away from the process for storage or further processing. Frequently, the separated hydrocarbon products contain coke particles, particularly when fluidized bed coking is employed. Such coke particles may range in size upwards from submicron to several hundred microns, typically, submicron to about 50 xcexcm. It is generally desirable to remove particles larger than about 25 xcexcm to prevent fouling of downstream catalyst beds used for further processing. Filters, located downstream of the separation zone, are employed to remove coke from the products. Undesirably, solid hydrocarbonaceous particles present in the separated lower boiling hydrocarbon products may physically bind to each other and the filters, thereby fouling the filter and reducing filter throughput. Fouled filters must be back-washed, removed and mechanically cleaned, or both to remove the foulant.
There is therefore a need for a method for reducing foulant agglomeration in petroleum coking product streams.